1. Field of the Invention
This invention relates generally to outboard marine bearings and particularly to stave pads wherein the bearing surfaces providing sliding support for a rotatable shaft are contoured or otherwise arranged to have a wider pressure profile for increased load carrying capacity.
2. Brief Description of the Prior Art
There have been considerable development in the use of water lubricated bearings for carrying rotatable shafts such as propeller shafts. Resilient elastomeric bearings commonly formed from rubber have been found especially suitable for this use. They provide the necessary corrosion resistance and function well under slight shaft misalignments. An early type of elastomeric bearing for marine use employed a simple sleeve with its outer surface secured in a housing. Further developments resulted in grooves being provided on the bearing surface to aid distribution of water for lubrication. More recent developments have concerned removable stave pads spaced apart about the inner periphery of a housing and capped with resilient faces of elastomer, such as rubber, for supporting a rotatable shaft. The staves include rigid backing strips usually contoured to a shape adapted for easy fitting into dovetail slots about the inner periphery of the housing. Leading edges of the resilient bearing have been tapered or relieved in some manner for encouraging the entry of lubrication to the bearing surface. Resilient bearing material may wear down under heavy loading from insufficient lubrication, thus presenting a wiping edge at the leading edge of the pad. This prevents entry of water between the bearing and shaft. U.S. Pat No. 2,898,165 illustrates, for example, one method of increasing the flow of lubricant (water) between the resilient bearing surface and the shaft by relieving bearing pressure at the leading edge of the stave pad. This is accomplished by inserting a strip of relatively soft rubber at the leading edge of the pad, or by relieving a portion of the underlying metal backing at the leading edge and increasing the height or thickness of the rubber, thus decreasing its resistance to deformation. The art is replete with ideas directed to enhancing the entry of lubricant between the bearing and shaft.